Effects Of Feeding Schemes Of Milk On Growth Performance,blood Parameters And Rumen Development In Dairy Calves

Feeding management in the dairy calves is critical to the production performance of dairy cows and directly affects the economic benefits of intensive dairy farms.The dairy calves have the characteristics of fast growth and development,high feed utilization rate and great development potential.Good development of the rumen is essential for the breeding of dairy calves.Different feeding amount of milk may affect starter feed intake,thus affecting the rumen development of the dairy calves,which in turn affects the growth performance of dairy cows.In this study,three different feeding programs were set up to evaluate the effects of three different feeding programs by measuring the growth performance,blood parameters and rumen development of the dairy calves,in order to provide reference data for dairy farm.Experiment 1 Effects of different feeding programs on growth performance and healthy status of the dairy calvesIn this experiment,27 male Holstein calves with a body weight of 40±3 kg and a birth time difference of less than 24 h were randomly divided into 3 groups,with 9 calves per group.Three different feeding schemes were performed with the same milk feeding amount(453 L)and weaning time(70 days old)with a trial period of 100 days.The three treatment groups were the control group(Group A): the daily feeding amount was constant with age;the feeding scheme 1(Group B): the daily milk feeding amount increased firstly and then decreased with age,and the amount of later milk feeding was large;the feeding scheme 2(Group C): the daily milk feeding amount increased firstly and then decreased with age,and the amount of later milk feeding was small.The results showed that the feeding program of Group C significantly increased the 100-day-old body weight and the average daily weight gain of 0-100 days(P< 0.05),and increased the 70-day-old body weight and the average daily weight gain of 0-70 days.(P = 0.068 and P = 0.093).The feeding program of Group C significantly increased the weight gain from 0-100 days(P< 0.05)and increased the trend of weight gain from 71-100 days(P = 0.093).The feeding program of Group C had a tendency to decreased the feed-to-weight ratio of 0-100 days(P = 0.059).The dairy calves of Group B occurred diarrhea at 12 days old,which was the earliest time amongthe three groups.The lowest diarrhea rate was 1.9%,which was appeared in the Group C.The Group C received the lowest proportion of antibiotics + Daco feeding,which was 33.34%.For each additional weight of 1 kg of calf weight,the Group C has a minimum cost of 20.26 CNY,Group B has a cost of 20.79 CNY and Group A has a maximum cost of 20.87 CNY.The results showed that,in the three feeding programs,the Group C group had the best feeding effects,which was beneficial to reduce the diarrhea rate and diarrhea severity,increase the 100-day-old body weight,average daily weight gain of 0-100 days and the economic benefits of calves breeding.Experiment 2 Effects of different feeding programs on blood parameters and rumen development of the dairy calvesIn this experiment,the serum,rumen and intestinal tract of the 100-day-old calves of the first test were used as samples to measure blood biochemical indicators,antioxidant and immune indexes,and the pH of the rumen fluid and rumen tissue development.The results showed that the feeding program of Group C significantly increased serum globulin content(P< 0.05)and had a tendency to increase serum total antioxidant capacity(P = 0.091).The feeding program of Group C significantly increased serum immunoglobulin G(IgG)levels and decreased serum tumor necrosis factor(TNF-?)levels(P = 0.083).The thickness of the rumen back sac in Group C was higher than that in Group A(P = 0.088).The feeding program of Group C significantly increased the length of the nipple in rumen back sac(P< 0.05),and the feeding program of Group B and C significantly increased the length of nipple in rumen ventral sac(P< 0.05).The results showed that,in the three feeding programs,the feeding program of Group C was most beneficial to improve serum immunity and anti-oxidation function,which was beneficial to increase the length of rumen nipple and improve the absorption function of rumen wall.In summary,the feeding program of Group C was beneficial to promote the growth of the dairy calves,reduced the diarrhea rate,improved the economic benefits of dairy farms,and improved the antioxidant and immune function of the dairy calves,and improved the absorption function of rumen wall to some extent.The beneficial effects on dairy calvesgrowth performance and diarrhea,caused by the feeding program of Group C,may be related to the improvement of rumen absorption function and antioxidant and immune function,respectively.